U.S. patent application number 10/345620 was filed with the patent office on 2004-07-22 for method and apparatus for determining a concentration of a component in an unknown mixture.
Invention is credited to Dalmia, Avinash, Prohaska, Otto J..
Application Number | 20040142489 10/345620 |
Document ID | / |
Family ID | 32711962 |
Filed Date | 2004-07-22 |
United States Patent
Application |
20040142489 |
Kind Code |
A1 |
Prohaska, Otto J. ; et
al. |
July 22, 2004 |
Method and apparatus for determining a concentration of a component
in an unknown mixture
Abstract
The invention relates to a method and apparatus for determining
a concentration of a component in an unknown mixture. The method
includes the steps of preparing a reactant having a specified pH
level and a specified temperature and combining the unknown mixture
with the reactant. The method further includes varying the pH level
and temperature of the combination of the reactant and the unknown
mixture to facilitate converting at least one selected component.
Upon varying the pH level and temperature, the method will release
volatiles from the selected component(s). Based on these released
volatiles, which indicate the concentration of the selected
component(s), the method detects the indication. The apparatus for
determining a concentration of a component in an unknown mixture
includes a container having a specified volume, a reactant chamber,
and a sample chamber. The receptacle contains a reactant, placed
within the reactant chamber, having a predetermined pH level and a
predetermined volume. The receptacle also has a headspace sampling
interface in contact with the container for permitting connection
to a headspace sampling device and a sample introduction interface
for permitting connection to a sample injector to introduce a
sample into the sample chamber.
Inventors: |
Prohaska, Otto J.; (Danbury,
CT) ; Dalmia, Avinash; (Hamden, CT) |
Correspondence
Address: |
ST. ONGE STEWARD JOHNSTON & REENS, LLC
986 BEDFORD STREET
STAMFORD
CT
06905-5619
US
|
Family ID: |
32711962 |
Appl. No.: |
10/345620 |
Filed: |
January 16, 2003 |
Current U.S.
Class: |
436/181 ;
422/82.12; 422/83; 436/127; 436/147; 436/163 |
Current CPC
Class: |
G01N 1/2226 20130101;
G01N 2001/2229 20130101; Y10T 436/20 20150115; Y10T 436/25875
20150115; G01N 35/1097 20130101 |
Class at
Publication: |
436/181 ;
436/163; 436/147; 436/127; 422/083; 422/082.12 |
International
Class: |
G01N 001/22 |
Claims
What is claimed is:
1. A method for determining a concentration of a component in an
unknown mixture, comprising: preparing a reactant having a
specified pH level and a specified volume; combining the unknown
mixture with the reactant; varying the pH level of the combination
of the reactant and the unknown mixture to facilitate converting at
least one selected component; varying the temperature of the
combination of the reactant and the unknown mixture to facilitate
converting the at least one selected component; oxidizing the
combination of the reactant and the unknown mixture to facilitate
converting the at least one selected component; reducing the
combination of the reactant and the unknown mixture to facilitate
converting the at least one selected component; releasing volatiles
from the at least one selected component; and detecting an
indication of a concentration of the at least one selected
component based on the released volatiles.
2. The method according to claim 1, further comprising the step of
transforming the at least one selected component to a gaseous
phase.
3. The method according to claim 1, further comprising the step of
determining a concentration of the at least one selected component
in the unknown mixture based on the detected indication.
4. The method according to claim 1, further comprising the step of
determining a dissociation constant of the at least one selected
component and adjusting the pH level of the reactant based on the
dissociation constant.
5. The method according to claim 4, further comprising the step of
raising the pH level above the dissociation constant to suppress at
least one unselected component from releasing volatiles.
6. The method according to claim 4, further comprising the step of
lowering the pH level below the dissociation constant to facilitate
releasing volatiles from the at least one selected component.
7. The method according to claim 1, further comprising the step of
combining the unknown mixture in a basic solution.
8. The method according to claim 1, further comprising the step of
combining the unknown mixture in an acidic solution.
9. The method according to claim 1, further comprising the step of
suppressing at least one unselected component in the unknown
mixture to hinder the at least one unselected component from
releasing volatiles.
10. The method according to claim 1, further comprising the step of
converting the at least one selected component.
11. A method for determining a concentration of a component in an
unknown mixture, comprising: preparing a reactant having a
specified pH level; combining the unknown mixture with the
reactant; varying the pH level of the combination of the reactant
and the unknown mixture to facilitate converting at least one
selected component; releasing volatiles from the least one selected
component; and detecting an indication of a concentration of the at
least one selected component based on the released volatiles.
12. The method according to claim 11, further comprising the step
of determining a concentration of the at least one selected
component in the unknown mixture based on the detected
indication.
13. The method according to claim 11, further comprising the step
of suppressing at least one unselected component in the unknown
mixture to hinder the at least one unselected component from
releasing volatiles.
14. A method for determining a concentration of a component in an
unknown mixture, comprising: preparing a reactant having a
specified temperature; combining the unknown mixture with the
reactant; varying the temperature of the combination of the
reactant and the unknown mixture to facilitate converting at least
one selected component; releasing volatiles from the least one
selected component; and detecting an indication of a concentration
of the at least one selected component based on the released
volatiles.
15. The method according to claim 14, further comprising the step
of determining a concentration of the at least one selected
component in the unknown mixture based on the detected
indication.
16. The method according to claim 14, further comprising the step
of suppressing at least one unselected component in the unknown
mixture to hinder the at least one unselected component from
releasing volatiles.
17. A method for determining a concentration of a component in an
unknown mixture, comprising: preparing a reactant having a
specified pH level and a specified volume; combining the unknown
mixture with the reactant; converting the at least one selected
component; releasing volatiles from the at least one selected
component; and detecting an indication of a concentration of the at
least one selected component based on the released volatiles.
18. The method according to claim 17, further comprising the step
selected from the group consisting of varying the temperature of
the combination of the reactant and the unknown mixture, varying
the pH level of the combination of the reactant and the unknown
mixture, oxidizing the combination of the reactant and the unknown
mixture, reducing the combination of the reactant and the unknown
mixture, and combinations thereof.
19. An apparatus for determining a concentration of a component in
an unknown mixture, comprising: a container having a specified
volume; said container having a reactant chamber and a sample
chamber; a reactant having a predetermined pH level and a
predetermined volume placed within said reactant chamber; a
headspace sampling interface in contact with said container for
permitting connection to a headspace sampling device; and a sample
introduction interface for permitting connection to a sample
injector to introduce a sample into said sample chamber.
20. The apparatus according to claim 19, wherein said sample
chamber contains an unknown mixture of components.
21. The apparatus according to claim 20, further comprising a mixer
in contact with said container for mixing said reactant and said
sample.
22. The apparatus according to claim 19, wherein said container
further comprises a separable mechanism for separating said
reactant chamber from said sample chamber.
23. The apparatus according to claim 22, wherein said separable
mechanism is removable so that said reactant is combined with the
sample.
24. The apparatus according to claim 20, wherein said sample is
selected from the group consisting of the liquid phase, solid
phase, gas phase, and combinations thereof.
25. The apparatus according to claim 19, further comprising a valve
mechanism for permitting a predetermined amount of the sample to
enter said container.
26. The apparatus according to claim 19, further comprising a
second reactant chamber and a second reactant placed in said second
reactant chamber, said second reactant having a predetermined pH
level and a predetermined volume.
27. The apparatus according to claim 26, further comprising a
second separable mechanism for separating said reactant chamber
from said second reactant chamber.
28. The apparatus according to claim 27, wherein said second
separable mechanism is removable so that said reactant is combined
with said second reactant.
29. An apparatus for determining a component in an unknown mixture,
comprising: a container having a specified volume; said container
having a reactant chamber and a sample chamber; a reactant having a
predetermined pH level and a predetermined volume placed within
said reactant chamber; a headspace sampling interface in contact
with said container for permitting connection to a headspace
sampling device; a sample introduction interface for permitting
connection to a sample injector to introduce a sample into said
sample chamber; a heating element in contact with said container
for heating said container; a timer for setting a heating time for
said heating element to heat said container; a headspace sampling
device coupled to said headspace sampling interface for measuring
volatile releases from said sample; and an electronic circuit in
contact with said heating element, said timer, and said headspace
sampling device for actuating said heating element, said timer, and
said headspace sampling device.
30. The apparatus according to claim 29, further comprising an
electrochemical gas sensor for sensing volatile releases in said
container.
31. The apparatus according to claim 29, wherein said sample
chamber contains an unknown mixture of components.
32. The apparatus according to claim 31, further comprising a mixer
in contact with said container for mixing said reactant and said
sample.
33. The apparatus according to claim 29, further comprising a
plurality of containers of varying sizes and having varying volumes
of reactants with varying pH levels.
34. The apparatus according to claim 33, further comprising a
receiver capable of receiving any one of said plurality of
containers.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a method and apparatus for
determining an amount of a component present in a mixture.
BACKGROUND OF THE INVENTION
[0002] Manners for detecting an amount of a desired component in an
unknown mixture of components have evolved from simple mechanisms,
such as chromatography and lithographs, to more complex and
accurate mechanisms, such as sensors. Sensors are known to detect a
concentration of a component introduced into the sensor.
[0003] However, false or inaccurate readings may occur if multiple
gases are introduced across the sensor's sensing electrode because
the sensor may sense gases not desired to be targeted by a user.
Increasing the number of gases across the sensing electrode
generally increases error. This problem may worsen when multiple
gases having similar properties, such as chemical and/or electrical
properties, come in contact with the sensing electrode, typically
resulting in difficulty distinguishing a targeted component from
other components having similar characteristics.
[0004] Additionally, inconsistencies in the testing environment may
lead to repeatability problems, where a reading may not be
confirmed by repeating the experiment without introducing
additional deviation error. For example, a technician desiring to
detect a selected gas at the sensing electrode may, during the
experiment, need to mix a mixture of gases with a reactant in order
to vaporize the selected gas. Measuring a precise amount of the
reactant or varying the reactant's physical properties, in order to
facilitate vaporizing the gas, often results in each reading being
different from the next because repeatedly measuring a precise
amount or repeatedly varying the physical properties in the same
manners may prove difficult.
[0005] U.S. Pat. No. 6,143,246 to Lee et al. relates to an
apparatus for measuring ammonia in wastewater. The invention
discloses a method for adjusting the pH level of the sample to a
predetermined level for a predetermined amount of time. The method
further correlates the measurements of time and linear correlation
constants in an inventive formula to arrive at a calculated
concentration of ammonia. However, the reference is generally not
applicable for detecting a component other than ammonia. The
reference also does not typically relate to a method for detecting
ammonia in a mixed solution of unknown chemicals.
[0006] U.S. Pat. No. 5,976,465 to Luzzana et al. generally relates
to a method for determining a concentration of a sample by
measuring pH at the beginning and end of a reaction of the sample
with a reactant. The change in pH is indicative of the sample
concentration. Regulating temperature and minimizing the effects of
temperature on pH is disclosed. However, the reference does not
typically determine the concentration by measuring the sample
directly. Instead, the reference normally measures changes in the
pH level of the solution, the change in pH being indicative of the
sample concentration. This indirect measurement of the sample
concentration may introduce error into the readings because the
resulting differences in pH would likely entail converting the pH
difference to a concentration measurement. Furthermore, the
reference does not typically address or reduce the likelihood of
having undesired components participating in the reaction and
interfering with the desired component's measurement.
[0007] U.S. Pat. No. 5,991,020 to Loge relates to a method for
determining a concentration of atomic species in gases and solids.
The method requires measuring at least two emission intensities
from a species in a plasma containing the species after a
sufficient time interval and plasma has had an opportunity to be
generated. Concentration is then derived from emission intensities
of the desired species in the sample. Similar to Luzzana, this
reference often measures concentration indirectly. The
concentration is typically derived from measured intensities and it
is this extra step of derivation, a step obviated in direct
measurements of the sample concentration, that may cause error in
readings. Furthermore, the reference does not typically address or
reduce the likelihood of having undesired components participating
in the reaction and interfering with the desired component's
measurement.
[0008] No reference or combination of references discloses a method
for determining a concentration of a component dissolved in a
mixture of components by directly measuring the component.
Additionally, no reference reduces a likelihood of having undesired
components participating in the reaction and interfering with the
desired component's measurement. Furthermore, no reference
discloses a simple and easy-to-use device for enhancing
repeatability readings by reducing experimental or human error
during experiments.
[0009] What is desired, therefore, is a method for determining a
concentration of a component dissolved in a mixture of components.
What is also desired is a method of determining the concentration
by directly measuring the selected component. A further desire is
to reduce a likelihood of having undesired components participating
in the reaction and interfering with the desired component's
measurement. A still further desire is to provide a device that is
simple and easy to use that enhances repeatability readings and
reduces experimental error.
SUMMARY OF THE INVENTION
[0010] Accordingly, it is an object of the invention to provide a
method for determining a concentration of a component in an unknown
mixture.
[0011] Another object of the invention is to provide a method for
substantially transforming a selected component, originally
combined in the unknown mixture, into a gaseous phase.
[0012] A further object of the invention is to provide a method for
inhibiting unselected components of the mixture from transforming
to a gaseous phase and interfering with detection of the selected
component.
[0013] Still another object of the invention is to provide a device
that is simple and easy to use to enhance repeatability
readings.
[0014] Yet another object of the invention is to provide a device
that reduces experimental error.
[0015] These and other objects of the invention are achieved by
provision of a method for determining a concentration of a
component in an unknown mixture of components. The method includes
the steps of preparing a reactant having a specified pH level and a
specified volume and combining the unknown mixture with the
reactant. The method further includes varying the pH level and
temperature of the combination of the reactant and the unknown
mixture to facilitate converting at least one selected component.
Upon varying the pH level and temperature, the method will release
volatiles from the selected component(s). The method then detects
these released volatiles, which indicate the concentration of the
selected component(s).
[0016] The method further includes the step of calculating the
concentration of the component(s) in the unknown mixture based on
the detected volatiles, or indication. Prior to detecting the
indication of the concentration of the selected component(s), the
method transforms the selected component(s) to a gaseous phase.
[0017] In conjunction with varying the pH level and temperature of
the combination of the reactant and the unknown mixture, the method
may include determining a dissociation constant of the selected
component and adjusting the pH level of the combination relative to
the dissociation constant to facilitate releasing volatiles from a
desired component and/or suppressing the release of volatiles from
undesired components.
[0018] In another aspect of the invention, a receptacle is provided
for determining a concentration of a component in an unknown
mixture. The receptacle includes a container having a specified
volume, a reactant chamber, and a sample chamber. The receptacle
contains a reactant, placed within the reactant chamber, having a
predetermined pH level and a predetermined volume. The receptacle
also has a headspace sampling interface in contact with the
container for permitting connection to a headspace sampling device
and a sample introduction interface for permitting connection to a
sample injector, which introduces a sample into the sample chamber.
Optionally, the sample introduction interface may be coupled to a
valve for permitting a fixed amount or volume of the sample to
enter the container.
[0019] The receptacle further includes the unknown mixture placed
in the sample chamber. In certain embodiments, the receptacle
includes a mixer in contact with the container for mixing the
reactant and sample.
[0020] The receptacle also includes a separable mechanism for
separating the reactant chamber from the sample chamber. The
separable mechanism is removable or has a portion that is removable
so that the reactant and sample may be combined.
[0021] In further embodiments, the receptacle includes a second
reactant placed in a second reactant chamber for further
combination with the first reactant and mixture. In these
embodiments, there is also a separable membrane separating the
reactant chambers and mixture.
[0022] In another aspect of the invention, the apparatus for
determining a component in an unknown mixture further includes, in
addition to the receptacle described above, a heating element in
contact with the container for heating the contents of the
container. The apparatus also includes a timer for setting a
heating time for the heating element, a headspace sampling device
coupled to the headspace sampling interface, and an electronic
circuit in contact with, and for actuating, the heating element,
the timer, and the headspace sampling device.
[0023] The headspace sampling device may include an electrochemical
gas sensor for sensing volatile releases in the container.
[0024] It should be understood that the apparatus is capable of
receiving any one of a plurality of containers of varying sizes and
having varying volumes of reactants with varying pH levels. To this
end, the apparatus includes a receiver to accommodate any one of
the plurality of containers.
[0025] The invention and its particular features and advantages
will become more apparent from the following detailed description
considered with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 depicts a method for determining a concentration of a
component in an unknown mixture in accordance with the
invention.
[0027] FIG. 2 more particularly depicts the conversion and
suppression steps of the method shown in FIG. 1.
[0028] FIG. 3 depicts an apparatus for practicing the method shown
in FIG. 1.
[0029] FIG. 4 depicts further features of the apparatus shown in
FIG. 3 and for practicing the method shown in FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 depicts the method 10 for determining a concentration
of a component in an unknown mixture in accordance with the
invention. Method 10 determines the concentration of a component in
a liquid or solid phase by transforming the component to a gaseous
phase. Once in the gaseous phase, the component is detectable by a
detection unit, such as an electrochemical gas sensor or other unit
for detecting vapors. Method 10 further includes steps for
enhancing conversion of the selected, or desired, component 34 and
steps for suppressing, or inhibiting, the conversion of unselected
components.
[0031] As shown in FIG. 1, method 10 includes the step of preparing
32 a reactant having a specified pH level, a specified volume, and,
optionally, a specified temperature and then combining 24, or
mixing, the prepared reactant with a mixture 16 of known
components. Although method 10 would properly function if the pH
level, temperature, or volume of the reactant were not known,
eliminating as many variables from method 10 increases the
likelihood of yielding an accurate concentration determination of
selected component 34. Mixture 16 contains, among other components,
the component 34 to be selected for determining its
concentration.
[0032] In the preferred embodiment, although mixture 16 contains
various components, an operator using method 10 should know the
general total volume of mixture 16. Similar to the reasons for
knowing the volume of the reactant, knowing the volume of mixture
16 reduces the number of variables for which to solve, thereby
yielding a more accurate concentration determination. In other
embodiments, method 10 may be practiced with an unknown volume of
mixture 16. However, in these embodiments, accuracy may be
compromised.
[0033] Because the volume of mixture 16, volume of the prepared
reactant, as well as the pH level and temperature of the reactant,
are within the control of the operator, the operator may eliminate
these variables.
[0034] Further, an operator using method 10 should also determine,
or select, the component 34 for analysis in which its concentration
is determined. Moreover, although mixture 16 contains numerous
components, the operator need not know the identity of all of the
components. The operator needs to know that selected component 34
is in mixture 16, albeit in the liquid or solid phase.
[0035] To determine the concentration of selected component 34,
method 10 converts 40 selected component 34, or transforms
component 34 to a gaseous phase. Converting 40 selected component
34 is particularly important because the more efficiently selected
component 34 is converted, the more accurately the concentration
may be determined. Efficient conversion is defined to be
transforming a substantial percentage of selected component 34 from
a liquid or solid phase to a gaseous phase. Transforming 100% of
selected component 34 is ideal but not required for method 10 to
properly function. The more efficiently, or closer to 100%,
selected component 34 is converted, or transformed to a gaseous
phase, the greater the amount of gas created and the more volatiles
are released, which is representative of the amount, or
concentration, of selected component 34. This leads to a more
accurate concentration determination, whereas transforming a small
amount of selected component 34 to a gas may lead to a lower
concentration determination than is present in mixture 16.
Similarly with knowing the volume of mixture 16 and other variables
related to the prepared reactant, efficiently converting 40
selected component 34 improves the likelihood of a more accurate
concentration determination. The steps of converting 40 selected
component 34 and suppressing 32 unselected components will be more
particularly described under FIG. 2.
[0036] After selected component 34 has been converted 40, volatiles
are automatically released from selected component 34, which is now
in the gaseous phase. Volatiles are defined to be contaminants,
bacteria, or any kind of releases indicative of selected component
34. It is these volatiles, or indications 26 of selected component
34, that are subsequently detected by the detection unit, such as
an electrochemical gas sensor or other unit for detecting vapors.
Hence, detecting a concentration of selected component 34 is
performed by detecting 28 indications of selected component 34,
such as the volatile releases.
[0037] Method 10 further includes calculating 30 the concentration
of selected component 34 and reporting 38 the concentration.
Calculating 30 the concentration is performed using correlation
information, such as the following formula, to correlate the amount
of indications 26, or volatiles, detected by the detection unit and
the amount, or concentration, of selected component 34 originally
in mixture 16.
[0038] The liquid and gas phases of component 34 may be expressed
in the following equation:
pKa=pH+Log.sub.10((Component in gas phase/Component in liquid
phase)) formula 1
[0039] where pKa is a known constant, pH of the Combination is
measured, gas phase of component 34 is also measured, or detected
28, and the liquid phase of component 34 is to be solved.
[0040] Based on the above formula 1, and solving for the component
is the gaseous phase, we find that if pKa-pH results in a number
less than zero, then the component in the liquid phase is greater
in concentration than the component in the gas phase, or the liquid
has a concentration ratio greater than gas. If pKa-pH results in a
number greater than zero, then the component in the gaseous phase
is greater in concentration than the component in the liquid phase,
or the gas has a concentration ratio greater than liquid.
[0041] In further embodiments where pKa-pH results in a number less
than -1, then the component in the liquid phas is dominant, or the
liquid has a concentration at least 10 times greater than the
concentration of gas. If pKa-pH results in a number greater than 1,
then the component in the gaseous phase is dominant, or the gas has
a concentration at least 10 times greater than the concentration of
liquid. Because the gaseous component is to be detected, it is
preferred that the gaseous phase be dominant over the liquid
phase.
[0042] By lowering the pH level of the Combination below the pKa
constant, selected component 34 is more likely to vaporize and,
specifically, more likely to efficiently vaporize because the
result of pKa-pH is greater than zero.
[0043] Reporting 38 the concentration is performed through all
known or novel manners for reporting information, such as merely
displaying the concentration on a monitor or LCD. Reporting 38 may
also be storing or sending the concentration to a computer or other
storage device. Reporting 38 is not germane to the invention and
should not be a limitation of method 10.
[0044] FIG. 2 more particularly depicts the steps for converting 40
selected component 34 and suppressing 32, or inhibiting, unselected
components from conversion.
[0045] After the desired component has been selected 34 for
analysis by an operator, converting 40 selected component 34
entails practicing steps to facilitate transformation of selected
component 34 from a liquid or solid phase to a gaseous phase.
Converting 40 includes determining a disassociation constant ("pKa
constant") of selected component 34 and adjusting the pH level of
the combination of the reactant and mixture 16 ("Combination")
relative to the pKa constant, which is an indication of the
component's ability to partition between liquid and gas phases.
[0046] In the embodiment shown in FIG. 2, lowering 42 the pH level
is one of several steps that facilitate converting 40 selected
component 34. However, lowering 42 the pH level is not universally
applicable to convert 40 all selected components. In other
embodiments, not shown, raising the pH may facilitate converting 40
selected component 34. The raising or lowering of the Combination's
pH level for facilitating converting 40 selected component 34
depends on the type of component selected for analysis and the
mixture in which the component is placed.
[0047] Additionally, converting 40 includes varying a temperature
of the Combination. For example, when practicing method 10 for
converting the selected component, such as H.sub.2S, the
temperature is typically raised to between approximately 50.degree.
C. and 80.degree. C. and, preferably, approximately 80.degree. C.
However, this 80.degree. C. temperature is merely an example and
may vary to convert different components or compounds from
different mixtures 16. Furthermore, this temperature was
empirically determined for converting SO.sub.2 and later
experiments above or below 80.degree. C. may be used with respect
to converting SO.sub.2.
[0048] In the embodiment shown in FIG. 2, raising 44 the
temperature is another step that facilitates converting 40 selected
component 34. However, raising 44 the temperature is not
universally applicable to convert 40 all selected components. In
other embodiments, not shown, lowering the temperature may
facilitate converting 40 selected component 34. The raising or
lowering of the Combination's temperature for facilitating
converting 40 selected component 34 depends on the type of
component selected for analysis and the mixture in which the
component is placed.
[0049] Further, by increasing the temperature, undesired
interferences may be suppressed, which facilitates detection of
desired components. For example, SO.sub.2, which may interfere with
the detection of H.sub.2S, is converted to SO.sub.3 at higher
temperatures, such as 80.degree. C. SO.sub.3 is not active, or does
not provide an electrochemical signal that may interfere with the
detection of H.sub.2S and, hence, the detection of H.sub.2S is
facilitated.
[0050] Additionally, as shown in FIG. 2, converting 40 selected
component 34 may also include oxidizing or reducing the
Combination. Oxidation and reduction include all known or novel
procedures in the art for oxidizing or reducing the
Combination.
[0051] In the embodiment shown in FIG. 2, oxidizing 46 the
Combination is another step that facilitates converting 40 selected
component 34. However, oxidizing 46 the Combination is not
universally applicable to convert 40 all selected components. In
other embodiments, not shown, reducing the pH may facilitate
converting 40 selected component 34. Whether to oxidize or reduce
the Combination for facilitating converting 40 selected component
34 depends on the type of component selected for analysis and the
mixture in which the component is placed.
[0052] In further embodiments, selected component 34 may be a
compound that efficiently transforms to a gaseous phase without
adjusting the pH level or temperature of the Combination or without
oxidation or reduction. Hence, selected component 34 is efficiently
converted due to the chemical properties of selected component 34
among the other compounds in mixture 16 and/or the reactant.
[0053] In some instances, converting 40 selected component 34 may
cause other, unselected components to also convert. This is because
converting entails subjecting the Combination of both the reactant
and mixture 16 to the same temperature and/or pH adjustments. For
components having similar chemical properties as selected component
34, these components may be inadvertently converted along with
selected component 34. In cases where conversion affects unselected
components, suppression in addition to or instead of conversion may
remedy the problem of inadvertently converting unselected
components.
[0054] Suppressing 32 unselected components inhibits the unselected
components from conversion. Suppressing 32 includes adjusting the
pH level of the Combination relative to the pKa constant. For the
example shown in FIG. 2, unselected components may be suppressed by
raising 52 the pH level above the pKa constant and lowering 54 the
temperature of the Combination.
[0055] Similar to the step for converting 40 selected component 34,
the degree of raising 52 the pH level or lowering 54 the
temperature varies according to the type of selected component 34
and mixture 16 in which selected component 34 is placed. Further,
depending on these factors, the temperature may be raised in order
to suppress 32 unselected components.
[0056] Additionally, the degree of reducing 56 the Combination for
facilitating suppression 32 of unselected components from being
converted varies according to the type of selected component 34 and
mixture 16 in which selected component 34 is placed. Further,
depending on these factors, the Combination may be oxidized in
order to suppress 32 unselected components.
[0057] As shown in FIG. 2, the Combination cannot have its pH level
lowered below the pKa constant to facilitate converting 40 selected
component 34 at the same time the pH level is raised above the pKa
constant to suppress unselected components. However, these steps
may be performed in sequence one after the other or spaced apart
after a time interval. Further, the Combination's pH may be
adjusted simultaneously or sequentially with the temperature for
facilitating conversion and suppression. The Combination may also
be oxidized and reduced independently from adjusting the pH and
temperature.
[0058] It should be understood that converting 40 selected
component 34 and/or suppressing 32 an unselected component does not
require any of the above steps of raising 44 or lowering 54 the
temperature and lowering 42 or raising 52 the pH level of the
Combination relative to the pKa constant. Oxidation or reduction
may also not be required for converting 40 selected component 34.
Converting 40 or suppressing 32 may entail practicing one, several,
all, or some combination of these steps. The steps method 10
practices for converting 40 and/or suppressing 32 depends upon the
type of selected component 34 and mixture 16 in which selected
component 34 is placed.
[0059] FIG. 3 depicts the apparatus 100 for determining a component
in an unknown mixture in accordance with the invention. Sample
preparation receptacle 110 provides a reactant having a specified
volume and specified pH level, among other known properties, such
as density, mass, temperature, and the like. Sample preparation
receptacle 110 aides an operator in practicing method 10,
particularly step one of method 10 embodied in FIG. 1 for preparing
a reactant having a specified pH level and a specified volume. By
having a predetermined pH and volume, receptacle 110 reduces
experimental error that may be introduced if the operator were to
measure pH and volume of the reactant, especially if the experiment
required this be done with particular precision or if the
experiment were repeated.
[0060] Receptacle 110 includes a container 112 having a specified
volume of containment, wherein container 112 further includes a
reactant 116 chamber for placing a reactant and a sample 118
chamber for placing a sample, or mixture 16, within container 112.
The reactant may be a liquid, solid, or gas. Depending on the type
of component selected for conversion or mixture 16, the reactant's
phase may vary.
[0061] Container 112 further includes a headspace sampling 122
interface for coupling a detection unit, such as a headspace
sampling device, to container 112 for detecting the volatiles
released from the converted selected component 34. Another
detection unit may be a sensor, electrochemical gas sensor, or any
unit capable of detecting volatile releases from the converted
selected component 34.
[0062] Container 112 further includes a sample introduction 124
interface for providing an inlet for mixture 16, or the sample to
be analyzed, to enter container 112 and, more specifically, enter
sample chamber 118. To facilitate introducing a specific amount or
volume of mixture 16 into container 112, valve 132 is provided in
cooperation with sample introduction 124 interface.
[0063] Both headspace sampling 122 and sample introduction 124
interfaces are merely ports or connections and may have the same
limitations. The design of these interfaces or manners for coupling
with the detection unit or source for introducing mixture 16 should
not be a limitation of receptacle 110.
[0064] Receptacle 110 may further include a mixer 128 in contact
with container 112 for mixing the reactant and mixture 16 together
once both the reactant and mixture 16 have been placed in their
respective chambers. Mixer 128 may be internal, as shown in FIG. 3,
or external of container 112 and includes all known or novel mixers
for mixing liquids or solids or both. Mixer 128 may also be
inserted into container 112.
[0065] In addition to or instead of mixer 128, receptacle 110 may
further include a separable mechanism 130, such as a membrane, for
separating reactant 116 chamber from sample 118 chamber. Separable
mechanism 130 may be removable or have a portion of it that is
removable so that mixture 16 and the reactant may be combined.
Moreover, in certain embodiments, separable mechanism 130 may be
automatically dissolvable over time once mixture 16 has been added
to sample 118 chamber. This automatic dissolution may be due to the
chemical reaction between separable mechanism 130 and the reactant
or mixture 16. In further embodiments, separable mechanism 130 is
porous or has apertures for permitting the reactant and mixture 16
to mix.
[0066] In further embodiments, receptacle 110 includes more than
one reactant chamber. As shown in FIG. 4, a second reactant 117
chamber is used. Separable 130 mechanism separating reactant 116
chamber from second reactant 117 chamber includes all of the
limitations described above. In addition, the order of sample 118
chamber, reactant 116 chamber, second reactant 117 chamber, or any
additional reactant chamber is not to be a limitation on the
invention. Also, the order in which separable mechanism 130 is
removed or dissolved is not a limitation on the invention.
[0067] In addition to receptacle 110 and shown more particularly in
FIG. 4, apparatus 100 includes heating element 136 in contact with
container 112 for heating the contents of container 112, timer 138
for setting a heating time for heating element 136, headspace
sampling device 140 coupled to headspace sampling 122 interface for
measuring volatile releases from mixture 16, and electronic circuit
142 in connection with heating element 136, headspace sampling
device 140, and timer 138 for actuating and giving power for these
items to function properly.
[0068] Heating element 136 is any heat conducting device for
heating receptacle 110. Preferably, heating element 136 wraps about
receptacle to heat the contents of receptacle 110 evenly.
Desirably, heating element 136 should be adjustable such that when
heating element 136 is coupled to electronic circuit 142, an
operator operating electronic circuit 142 may vary the heat
intensity or power of heating element 136. In some embodiments,
heating device 136 is a heating coil. Heating element 136 may also
have an automatic shut off/turn on switch to maintain a desired
temperature.
[0069] Headspace sampling device 140 is any detection unit capable
of detecting volatiles indicative of selected component 34, such as
an electrochemical gas sensor or other unit for detecting
vapors.
[0070] Electronic circuit 142 is an electrical connection to power
heating element 136, timer 138, and headspace sampling device 140.
Electronic circuit 142 may also include controls for manipulating
the amount of power to, as well as adjusting the operation of, each
of these items. For example, electronic circuit 142 facilitates
setting timer 138, operating headspace sampling device 140, or
varying a temperature or intensity of heating element 136. In
certain embodiments, electronic circuit 142 performs what otherwise
would be manually laborious, tedious, or time consuming operations
and centralizes the operations in an electrical panel having
controls for each of the above mentioned items.
[0071] Apparatus 100 may further include receiver 144 for receiving
any one of a plurality of receptacles 110, where receptacles 110
vary in size, geometry, or weight. Receiver 144 may be a platform
for receiving and supporting any container 112 as well as heating
element 136.
[0072] Although the invention has been described with reference to
a particular arrangement of parts, features an the like, these are
not intended to exhaust all possible arrangements or features, and
indeed many other modifications and variation will be ascertainable
to those of skill in the art.
* * * * *